Well, there is a little bit more that we need to understand and do. Trees need to be planted at the correct depth. There's no "ifs, ands, or buts" about that.
To ensure that you plant the tree at the correct planting depth the hole needs to be the right size. Don't assume that the tree you are getting from the nursery was planted at the proper depth.
Many trees are purchase with extra soil piled over the root system covering the root collar (the area where the roots meet the trunk identified by the trunk flare), and this can be a problem. The extra soil can be traced back to common nursery practices.
When cultivating between rows, nurseries often build up soil around the trunk. When the trees are transplanted the root collar will be buried sometimes as much as six to nine inches.
If this excess soil is not removed, the root collar "suffocates." The problem caused by the excess soil results in a disruption of water and nutrient uptake, starting a downward spiral for the tree. These trees will probably not survive for more than two years although some will survive in a weakened state for 15 to 20 years until some other stress such as drought kills them.
Planting too deep is also likely the cause of girdling roots and nuisance root suckers.
As you are planting trees this spring, follow these steps to ensure proper tree planting:
- With balled and burlapped (B&B) trees, remove the twine around the trunk, peel the burlap back and remove if possible. Snip off wire baskets if present then gently scrape away excess soil to reveal the root collar. When planted at the proper depth the root collar (trunk flare) should be visible. If the trunk is as straight as a telephone pole, the tree has been planted too deep.
- If you are planting a tree that was in a container, carefully removed the container and check the roots. If they are tightly compressed or "potbound," use your fingers or a blunt instrument (to minimize root tearing) to carefully tease the fine roots away from the tight mass and then spread the roots prior to planting. In the case of extremely woody compacted roots, it may be necessary to use a spade to open up the bottom half of the root system.
The root system is then pulled apart or "butterflied" prior to planting. Loosening the root structure in this way is extremely important in the case of container plants. Failure to do so may result in the roots "girdling" and killing the tree. At the very least, the roots will have difficulty expanding beyond the dimensions of the original container.
- To plant a bare-rooted tree, first build a cone of earth in the center of the hole around which to splay the roots. Make sure that when properly seated on this cone the tree is planted so that the "trunk flare" is clearly visible and the "crown", where the roots and top meet, is about two inches above the soil level. This will allow for natural settling.
- Dig the hole as deep as the root ball and no deeper so the soil under the root ball is undisturbed. Good news since you won"t have to dig as deep a hole.
- Dig a hole two to three times as wide as the root ball. It is important to make the hole wide because the tree roots on the newly established tree must push through the surrounding soil to establish. The hole should look more like a saucer then a burial plot!
- Fill the hole, gently but firmly. Fill the hole about one-third full and gently but firmly pack the soil around the base of the rootball. If the tree is balled and burlapped, cut and remove the string and wire from around the trunk and top one-third of the rootball. Be careful not to damage the trunk or roots in the process. Next water your tree. Fill another one-third of the hole taking care to firmly pack soil to eliminate air pockets that may cause roots to dry out and water. Continue to do this until the hole is filled and the tree is firmly planted and watered.
- Do not add soil amendments. Old recommendations for adding soil amendments such as peat moss have been discarded. Simply use the soil (less the rocks) removed from the hole as backfill.
- Prune only broken or dead branches at planting time. Removing live branches removes a source of stored energy important in overcoming planting stress.
- Stake trees only when needed as in windy or high traffic areas. Wire, even if protected with garden hose, can damage the trunk. Use broad-banded materials such as strips of landscape fabric. Make sure that you check the lashings frequently and remove after one year.
- It is not recommended to apply fertilizer at the time of planting. So wait a year to fertilize and then use a slow release fertilizer.
- Add three to four inches of mulch such as wood chips around the tree. Mulch acts as a blanket to hold moisture, protect against harsh soil temperatures, both hot and cold, and reduce competition from grass and weeds. Make sure that the mulch does not contact the trunk. Placing mulch too close to the tree may cause decay of the living bark at the base of the tree but also provides a refuge for insects and rodents.
- Do not wrap trees during the growing season. Wrap can hold moisture next to the trunk and serve as a home for insects.
Trees are a long term investment. I"m not talking about just the financial invest that we put into them but there is also a mental and physical investment too. To ensure that our investment is long term, our first step to healthy trees is to make sure they are planted correctly. Trees fail to thrive more often due to poor planting than to insects and diseases.
If you are looking to plant trees this spring, do your homework first. Select the proper tree for your site. It is better to start out right then to have to make a lot of corrections along the way. Avoid the "it"s so pretty" impulse purchase. Select a tree with the correct mature height and one that will easily adapt to the soil and planting site that you have. Also be sure to check with your city before planting any trees on the city right-of-way as the city may require permits before planting.